Refining of animal and vegetable oils



Feb. 13, 1940. CLAYTON 2,190,594

I REFINING OF ANIMAL AND VEGETABLE OILS Filed March -50, 19:59 2 Sheets-Sheet 1 WA TEE Feb. 13, 1940.

B. CLAYTON REFINING OF ANIMAL AND VEGETABLE OILS Filed March 50,. 1939 2 Sheets-Sheei 2 Patented Feb. 13, 1940 UNITED STATES PATENT" orrlci:

REFINING OFANIMALANDVEGETABLE Benjamin Clayton, Houston, Tex., assignor to- Refinlng, Inc., Nevada Application March 30,

30 Claims.

This invention relates to the refining of vegetable and animal oils, and more particularly to a process in which non-sa'ponifying neutralizing agents are employed to neutralize free fatty acids in the oils in a manner markedly reducing refining losses. I

Non-saponifying neutralizing agents as distinguished from the caustic alkalies conventionally employed, do not attack neutral oil, and enable reflning losses due to saponiflcation of neutral oil to be substantially eliminated. I Examples of such non-saponifying alkalies are alkali salts of alkali or alkali earth metals, ammonia and various amines. Soda ash is a specific example of such a non-saponify'mg alkali which is extremely inexpensive and available in large quantities. However, prior to the present developments, soda ash or other non-saponifying neutralizing agents'have not been successfully employed commercially for the neutralization of the free fatty acids in vegetable and animal oils. Substantially complete neutralization with such materials as soda ash is difilcult to obtain, and separation of thesoap stock formed normally results in excessive entrainment of neutral oilin the soap stock and the presence of objectionable amounts of soap stock in the separated oil. Also,

carbon dioxide tends to form when soda ash is added to oils containing free fatty acids, intermarkedly less entrained oil than even soap stock produced by the usual caustic alkali refining.

Since the non-saponifying neutralizing agent does not attack neutral oil and the entrainment of neutral oil in the soap stock is reduced ma-' terially over prior processes, refining losses are minimized.

The employment of non-saponifying neutralizing agents ordinarily does not materially reduce the color of oil containing impurities. In accordance with the present invention, it has been found that the color of such oils can be markedly reduced in a neutralizing step employing these agents. Such color reduction, however, may not be suflicient when highly colored oils are being Reno, Nev., a corporation of 1939, Serial No. 265,030

treated. In such cases, it has been found that the color of the oil may be further reduced by adding a color reducing agent such as a small amount of an aqueous solution of caustic alkali to the neutralized oil and thereafter separating the color impurities from the oil. The color reduction during neutralization, however, minimizes the amount of color reducing-agent that so that a separate color reducing step is unnecessary.

The resulting oil usually contains small amounts of residual impurities such as soap and precipitated-gums and color impurities as well as small amounts of alkali. These residual impurities are efl'e'ctively removed by adding wash water to the oil and separating the water containing residual impuritiesfrom the oil, and then subjecting the oil to vacuum treatment to remove residual water, although other steps for removingthe residual impurities may be employed. The washed and dried oil is substantially completely neutralized and free-of residual impurities and is of excellent quality and meets the color requirements of the art.

The process of the present invention is preferably carried out as a once-through continuous process in which the neutralizing agent, color reducing agent, if employed, and washing water are mixed with the oil during-continuous flow thereof, any changes of temperatures in the oil or mixtures being producedduring continuous flow' and the separation steps performed by continuous centrifugal separation. I w I It is, therefore, an object of the present invention to provide animproved process of refining animaland vegetable oils in which non-saponifying neutralizing agents are employed to neutralize the free fatty acids and the refining losses are minimized.

Another object of the invention is to provide a process of' refining animal and vegetable oils in which soda ash solutions are employed in sufficient amount and in proper concentration to substantially completely'neutralize the oil and provide eflicient separation. of the soap stock from the ofl.

Another object of the invention is to provide a ratus disclosed, although other forms of ratus may be employed.

process in which free fatty acids are neutralized in animal and vegetable oils by non-saponifyin'g alkalies and the color of highly colored oils reduced while decreasing refining losses.

Another object of the invention is to provide a process of refining animal and vegetable oils in which a large amount of soda ash in the form of a solution of proper concentration is present during centrifugal separation of soap stock from the oil in order to minimize entrainment of oil in the soap stock.

A further object of the invention is to provide a continuous process of refining animal and vegetable oils employing non-saponifying alkalies as neutralizing agents so as to reduce refining losses and produce prime oils.

A still further object of the invention is to provide a continuous process of refining animal and vegetable oils in which the neutralizing and color reducing steps are separately performed so as to enable non-saponifying alkalies to be employed for neutralization while minimizing refining losses.

Other objects and advantages of the invention will appear in the following description thereof given in connection with the attached drawings of which:

Figural is a schematic diagram of an apparatus suitable for carrying out a continuous process in accordance with the present invention;

I Figure 2 is a similar diagram of an apparatus suitable for carrying out a modification of the neutralizing and soapstock separation step;

Figure 3 is a similar diagram of an apparatus suitable for carrying .out a further modified neutralizing and separation step; and

Figure 4 is a similar diagram of an apparatus for carrying out a still further modified neutralizing and separating step.

As an aid to understanding the invention, it will be described in connection with the appa- Referring more particularly to Figure 1, II indicatesa tank as a source of supply for the oil to be refined. The tank It may be provided with a heating coil II to bring the oil to a predetermined temperature at which the oil is fiowable. A tank I! may contain neutralizing agent and may be provided with a heating coil iii to heat the neutralizing agent to a desired temperature for mixing with the. oil. A stream of oil may be withdrawn from the tank l by a pump I4 and delivered through a heat exchange device I 5 to a flow mixing device IS. The heat exchange devicev l5 preferably includes a coil I! through which the oil is passed, which coilis positioned in a casing l8 through which any desired heatingmedium may be circulated. Neutralizing agent may be withdrawn from the tank I! by a pump is and delivered to the fiow mixer It. The pumps l4 and I9 are preferably arranged-to deliver accurately'proportioned streams of oil and neutralizing agent, respectively, to the mixer l6,

' and one way of accomplishing this is to drive the pumps II and I9 from a variable speed electric motor 20 with a variable speed device 2| positioned between the motor and the pump it. The flow mixing device may be of any suitable type capable of rapidly forming thorough mixture of oil and reagent. The mixing device disclosed in Patent No. 2,142,062is preferred; but other'devices such as a closed mechanical agitator or a colloid mill may be employed if desired. J

The oil and reagent are preferably mixed under amazes pressure and out of contact with the atmosphere.

The resulting mixture may be passed through a heat exchange device 22 similar to the heat exchange device !5 and delivered to one or more continuous centrifugal separators 23.

The neutralizing agent reacts with the free fatty acid and also precipitates gums and color impurities contained in the oil to form soap stock. This soap stocks is separated from the oil in the centrifugal separators 23 and discharged therefrom as the heavy efiluent through spouts 2 3 into receivers 25. 13 neutralized oil is discharged from the separatgirs through pipes 26 and is delivered into a receiver 27. By employing adueoussolutions of the neutralizing render the soap stock extremely fluid and soften the particles of soap and gums so that prolonged efiicient separation can be obtained. The centrifugal separators 23 are preferably of the heated type disclosed in Patent No. 2,100,277.

when highly colored ofls are being refined so that the color of the oil is not sufficiently low, the neutralized ofl may be withdrawn from the receiver 21 byAa proportioning pump 28 and delivered through a heat exchange device 29 to a flow mixer 30. Color reducing agent may be withdrawn from a tank 3| by a pump 32 and delivered to the flowmixer 30. The tank 3! maybe provided with a heating coil 33 to bring the color reducing agent to a desired mixing temperature. The heat exchange device 29 is ordinarily employed to reduce the temperature of the neutralized oil, as in most instances it is found that the color reducing reaction goes forward more efllciently at a relatively low temperathe mixer l6 previously described. The resulting mixture from the mixer 30 is preferably passed through a heat exchange device 34 in which the' mixture is maintained at a relatively low temperature and then through a heat exchange device ll! in which the temperature of the mixture is raised to that providing most effective separation of the color impurities from the refined oil.

.ture. ..The mixer 30 may be of the same type as The refined oil may be withdrawn from the receiver .0 by a pump II and delivered through a heat exchange device 42 to a flow mixer 4%.

Washing water may be withdrawn from a tank 44 by a pump 45 and delivered to the flow mixer 43. The tank ll may also be provided with a heating coil It for bringing the wash water to a I of the chamber.

- 2,190,594 desired temperature of mixing. The pumps 4| and may likewise be driven by a variable speed electric motor 41 with a variable speed device 48 between the motor and pump 45. The mixer 48 may also be of the same type as the r l8 previously described. The resulting m e I of oil and water is preferably passed through another heatexchange device 49 and delivered to one or more continuous centrifugal separators 59. The wash water containing residual impurities is separated as the heavier eiliuent and discharged through spouts 5| into receivers 52.

The washed oil is discharged as the lighter eliiu-.

ent through pipes 53 into receiver 54 from which it may be withdrawn by a pump 55 and delivered through a heat exchange device 58 into a vacuum chamber 51. The vacuum chamber 51 may be provided with an agitator 58 driven by a motor 59 and with a heating coil 69. Provision may also be made for introducing steam through a distributor 6| positioned inv the lower portion Water and other vaporizable materials are withdrawn through a pipe 62 to the condenser 63. These materials are condensed and delivered to a receiver 64. A vacuummay be maintained in-the chamber 51, condenser 63 and receiver 94 by means of a vacuum pump 65. The

dried oil may be continuously withdrawn from the vacuum chamber 51 by means of a pump 66 and subjected to further treatments found necessary or desirable.

Referring to Figure 2, the apparatus shown therein is suitable for carrying out a process in which neutralizing agent may be added in steps.

The neutralizing agent added in the different steps may be of the same or diflerent kind and may be of the same or different concentration. Also, the apparatus of Fig. 2 may be-employed to add diluting or soap stock softening agents before or; after addition of the neutralizing agent. In such akprocess, similar apparatus to that shown in Figure 1 may be employed for performing the primary mixing of neutralizing or diluting agent with the oil. Thus the oil may be withdrawn from the tank III by means of a pump |4, delivered through a heat exchange device|5 to a flow mixer I8. Neutralizing or other agent may be withdrawn from a tank |2 by a pump l9 and delivered to the mixer IS. The resulting mixture may then be passed through a heat exchanger 22. In carrying out the process corresponding to Figure 2, an additional tank 61 for additional neutralizing agent or other diluting agent may be provided. The additional agent in thetank 61 may also be brought to a desired mixing temperature by means of a heating coil 88 and may be withdrawn from the tank 61 by a pump 58 and delivered to a flow mixer 69 into which the mixture from .the heat exchange device 22 is also delivered. The mixture 59 may be of the same type as the mixer It. The resulting mixture from the mixer 69 is preferably passed through another heat exchange device 10 and delivered to the continuous cen-' trifugal separators 23, of Figure 1.

The apparatus shown in Figure 3 provides for batch mixing of neutralizing agent and oil. I In order to insure a continuous supply of mixture for centrifugal separation, two or more mixing devices 13 and 14 may be provided so that a mixture may be formed in one mixing while the mixture is being withdrawn from another mixing device. The mixing devices 19 and 14 may be of large size, such as the conventional batch kettles employed in batch refining of animal and vegetable oils, although smaller mixing devices are preferred unless the number of centrifugal separators employed is sufficient to enable the oil to be withdrawn from the mixing device within a few hours. The mixing devices 18 and 14 may be provided with agitators 15 driven from any suitable source of power through pulleys I5, and mayalso be provided with heating coils 11 for controlling the temperature during mixing. Oil may be delivered into the mixing devices 13 and I4 through pipes 18 and I9, and neutralizing agent maybe delivered into. the miifing devices through pipes 89 and 8|, respectively. The mixture may be withdrawn alternatively from the devices 13 and 14 by means of the pump 82 and delivered through a heat exchange device 83 to the centrifugal separators 23 of Figure 1. In such a process, mixing is ordinarily carried on at a relatively low temperature, and the heat excha e device 83 employed to-raise the temperatu I of the mixture to the desired separating temperature.

The apparatus of Figure 4 may be employed in a process in which batch mixing of neutralizing agent and oil is employed and an additional neutralizing agent or other solution added to the resulting mixture in flow. It may also be employed to add a diluting or other agent to the oil in the first mixing step and then mix the neutralizing agent in flow. For example, a mixing device 84, which may be similar to the mixing devices I3 and 14, may be employed for mixing the oil and neutralizing age'nt. Only one mixing device 84 is shown, but two 'or more may beemployed, as shown in. Figure 3. The mixing device 84 may likewise be provided with an agitator 85 and the heating coil 86. Oil and neutralizing agent may be delivered into the mixing device 84 through the pipes 81 and 88, re-

spectively. The mixture may be withdrawn from the mixing device 84 by means of a pump 89 and delivered through a heat exchange device 99 to a flow mixer 9|. 'Diluting or-additional neutralizing agent may be withdrawn from a tank 92 provided with a heating coil 93 and delivered by a pump 94 to the flow mixer 9|. The pumps 89 and 94 are also preferably arranged as proportioning pumpsand may be driven by' a motor 95 with a variable speed device 98 between the motor and the pump 94. The resulting mixture from the mixer 9| is preferably passed through a heat exchange device 95 and delivered to the centrifugal separators 23 of Figure 1. I v

In carrying out the process in the apparatus of Figure 1, the stream of oil may be preheated in to temperatures approaching the boiling point of water. It is not usually desirableto heat theoil in the tank l8 much above 100 F., as there is danger of damaging the oil and setting the color thereof it subjected to high temperatures for extended periods of time, particularly in contact with the atmosphere.-' Ordinarily, the neutralizing agent is heated in the tank l2 to approximately the temperature employed for mixf.

ing, but this neutralizing agent may be heated above the mixing temperature in order to impart additional heat to the mixture. The temperature found most suitable for separation in the centrifugal separators 23 will vary with different oils, but will ordinarily fall within temperatures between 120 and 210 F. However, as stated in my application Serial No. 259,502, filed March 3, 1939, this temperature can be at least as high as 250 F. As contra-distinguished from the standard commercial practices wherein caustic alkali is used as a neutralizing agent,

these higher temperatures, when employing a non-saponifying reagent, such as soda ash, according to this invention, may be employed without fear of saponification of neutral oil or the breaking up of the gums into inseparable form. When employing the soda ash in aqueous solution, the high temperatures will not break up the gums and the presence of water prevents the soap stock from going into solution in the ins single mixing operation in accordance with lgig. 1-. The concentration of the aqueous so lution of soda ash, will vary with different oils but will usually range between 12 and B.,-

although with certain oils it may be possible I to employ concentrations as low as 5 B., and

with other oils as high as B. In accordance with the present invention, an "extremely large excess of soda ash is employed. It has been found that if the amount of solution falls below a predetermined value for any given oil,

the oil eiiluent is muddy, that is to say, it contains unseparated soap stock. The same is true,

if the concentration of the solution falls below a given point corresponding to any par cular oil.- There is also a maximum concentration for any given oil above which effective separation is not obtained. If the amount of soda. ash employed is.too small, it is also found that carbon dioxide is liberated in the centrifugal separators and interferes with separation. However, a muddy oil eflluent usually occurs beforegassing in the centrifugals starts, if the amount of soda ash is progressively reduced. The primary reason for employing a large excess of neutralizing agent, even when soda ash is employed, is therefore not the prevention of the formation of carbon dioxide but the production of eflective'separatlon. It will be apparent that the smallest amount of soda ash which provides effective separation is desirably employed.

Since the soda ash does not attack neutral oil and a large excess thereof is employed, centrifugal separation may be carried on at relatively high temperatures, that is, temperatures in the upper portion of the range given. This factor, in conjunction with the. apparent'softening action of soda ash upon the soap stock, en-

ables a heavy eifluent containing very small amounts of entrained oil to be separated from .the oil. The-exact excess of soda ash employed with any given 011 depends upon the type of oil, the amount of free fatty acids contained therein, the amount of gums in the oil and the temperature of separation. In general, the amount of soda ash will fall between 5 and 12 times that necessary to neutralize the free fatty acids and will usually be between '7 and 12 times that necessary to neutralize although with some oils it may be possible to secure good resuits with excesses as low as three times the amount required to neutralize. The temperatures of separation usually found most efiicient lie between 160 and 200 F., and if suficient excess of soda ash is employed, no gassing or priming of the centrifugal separators occurs, although such priming many times occurs at temperatures in the neighborhood of 160 in prior processes, even when caustic soda in conventional amounts and concentrations was employed.

If the neutralized oil delivered into the receiver 27 is of sufliciently low'color, it may be delivered directly to the washing and dryingstep for removing residual impurities, so that the color reducing step of the present invention may be omitted.

color reduction. In the case of highly colored oil such as cottonseed oil, it is usually desirable to treat the oil with a caustic alkali in order further to reduce the color. It is preferred to add the color reducing agent in a separate step following neutralization and soap stock separation. The color reducing reaction ordinarily .is best performed at relatively low temperatures, and as the oil is usually delivered into the receiver 21 at a relatively high temperature, the heat exchange device 29 may be employed to reduce the temperature of the oil, althoughwith some oils it is found that reduction of temperature is unnecessary. Thus the temperature of mixing in the mixer 30 may range between 80 F. or lower up to 160 F. In most cases, temperatures between 80 and 100 F. produce the best results. The color reducing agent is ordinarily an aqueous solution of caustic soda, although other caustic alkalies such as caustic potash may be employed. Concentrations in the neighborhood of. 12 B. usually give the best results, although this concentration may vary between 8 and B. with different oils. A small amount of such solution,for example, to 4%is usually sufllcient to satisfactorily reduce color. The temperature of the color reducing agent will ordi narily be brought to approximately the temperature of the oil leaving the mixer 30, by may vary quite widely therefromas the small amount employed does not materiallychange the temperature of the mixture. As the color reducing reaction is in many cases increased byproviding a time of treatment at a relatively low temperature, a heat exchange device 34 may be employed to provide a treating time for the mixture, which treating time will rarely need to exceed five minutes. 7 i

As the most eilective,temperature of separation of color-impurities from the oil is usually higher than that at which the color reducing agent-is mixed with the oil, the heat exchange.

device 35. may be employed to raise the temperature of. the mixture. The mixture is then preferably continuously centrifugally separated in the centrifugal separators 36. The temperature of separation will usually fall between 100and 160 F. and will vary with different oils beingfrom the centrifugal separators 36 may contain small amounts of soap, gums and alkali. By admixing this with oil with washing water in amounts usually falling within the range of 5 and 15% and then centrifugally separating the water from the oil; the major portion of such impurities is removed. The centrifugal separation is ordinarily more eflicient at relatively high I temperatures, for example, temperatures between 100 and 200 F., which temperature may be in excess of the temperature of the oil delivered into the receiver 40. In such case, the heat exchange devices 42 and 49 may "be-employed to impart additional heat to the oil or mixture, re-

spectively, or both may be employed for this pur- Also, the washing water 'may be heated pose. in the tank 44 to a temperature above that of the oil entering the mixer 43 in order to supply additional heat thereto, although the temperature of the washing water may be below the temperature of the oil entering the mixer 43. An extremely efficient centrifugal separation can be performed in the centrifugal separators 50 such that water containing impurities from the oil but substantially free of neutral oil can be discharged as the heavy effluent from the separators.

The oil, however, usually contains a small amount of water and this can most efliciently be removed by delivering the oil into a vacuum dryer such as thevacuum chamber 51. If necessary, additional heat can be imparted to the oil by a heat exchanger 56. Also, additional heat can be imparted to the oil in the vacuum chamber 5] by means of a heating coil 60 positioned therein. Temperatures in the vacuum chamber will usually range between 160 and 200 F., and, by agitating the oil either by the mechanical agitator 58 or by passing superheated steam through the oilfro'm the distributor -6|, a substantially dry oil can be removed from the vacuum chamber by means of the pump 66. A relatively high vacuum, for example, between 2'1 and I 29 inches of mercury, is preferably maintained in the vacuum chamber. The vacuum chamber may also be employed to .deodorize the oil, par--' is possible to employ temperatures as high as 450 to 500 F. in the vacuum chamber in order to bleach the oil. I

As a modified operation, the oil may be first mixed with a lesser amount of soda ash solution than that necessary to produce effective separation in the centrifugal separators 23. Thus, in accordance with Figure 2, a portion of the soda ash solution may be added in the mixer l6. The amount added in mixer I6 will usually be considerably more than the amount to neutralize the free fatty acids, the remaining solution being added before separation takes place so thatnot less than three times the amount required to neutralize the free fatty acids shall be present at separation in order that the soap stock may be properly diluted and softened and the resultant mixture passed through a heat exchanger 10 before being delivered to the centrifugal separators 23 of Figure 1. The solution furnished from the tank 61 may be of. the sameconceritration as the solution delivered from the tank l2, but with certain oils it is sometimes desirable to employ an extremely concentrated soda ash solution in the mixer l6 and then add a more dilute solution in the mixer 69 so as to bring the concentration and amount of neutralizing agent in the mixture being separated to that which produces most eflicient results. Thus, highly concentrated solutions or slurries containing more soda ash than can be dissolved in water can be introduced into the mixer l6. It is even possible to employ dry soda ash in the first mixing zone if a suitable introducing mechanism such as a screw conveyor is employed. Very dilute solutions or even water alone may then be added inshown in Figure 3. In order to prevent formation of carbon dioxide,- it is usually necessary to carry on the mixing at a relatively low temperature, for example, temperatures between 80 and 100 F. By always maintaining a large excess of soda ash in contact with the oil throughout" the mixing operation, prevention of carbon dioxide formation can be accomplished, even at temperatures somewhat above those given. Thus, by adding a large excess of soda ash rapidly to a body of oil in a mixer 13 or 14 during rapid agitation, carbon dioxide formation can be prevented. It is also possible to first place the soda ash solution in the kettle and then add the oil during rapid agitation. After a thorough.

admixturehas been attained, the agitation maybe slowed to just that necessary to prevent strati flcation of the soap stock in the mixer and then reference to Figure 2, a portion of the soda ash may be added in the mixer 84 of Figure 4 and the remaining soda ash'added in flow in the mixer 9|. The concentration of the two additions may vary with different oils 'as described with reference to Fig. 2. That is tosay, even dry soda ash or water alone may be employed in one or the other of the mixing steps if the material added in the last mixing step brings the final mixture to the correct amount and concentration for effective separation. The heat exchanger may be employed to bring the mixture from the mixer 64 to a desired temperature for mixing additional neutralizing or diluting agent in the mixer 9|. The heat exchanger 95 may be employed to bring the resulting mixture to a desired separating temperature and the mixture then delivered to the centrifugal separators 23 of Figure 1.

In all of the operations above described, soda ash is the preferred neutralizing agent, and the process is particularly adaptable to low free fatty m acid oils. With such oils, it has been extremely difficult to even equal the results of the standard cup test for determining the losses to be expected in refining oil. In operations in accordance with the present invention, savings up to 50% of the losses indicated by the cup test have been obtained. With high free fatty acids, the amount of soda ash required for producing efficient separation of the soap stock from the oil may be less than that required to prevent formation of carbon dioxide therein. In such cases it is sometimes desirable to mix a small amount of caustic alkali such as caustic soda with the neutralizing agent to neutralize a portion of 'the free fatty acids. In order to prevent saponifi-r cation of neutral oil, the amount oi caustic alkali thus added should be materially less than that required to neutralize all of the free fatty acids. This caustic alkali is preferably added in the first mixing step if more than one mixing step 85 is employed prior to separation. With low free ,fatty acid oils, where the amount of soda ash solution necessary to provideefiective separation of the soap stock is greatly in excess of the amount required to prevent formation of carbon. dioxide during mixing, other materials, even substantially neutral salts, particularly those having soap stock softening properties, such as sodium sulfate, sodium thiocyanate etc may be substituted in part for the neutralizing agent do by mixing such salts with the neutralizing agent,

or in processes described with reference to Figures 2 and 4, such salts may be admixed with the oil before or after adding the neutralizing agent.

45 Although soda ash as the neutralizing agent has been found to give the best results, other non-saponifying alkalies such as alkali salts of alkali metals, for example, trisodium phosphate,

- disodium phosphate, sodium silicate,- and equivaso lent potassium salts; alkali salts of alkaline earth metals; and amines such as ammonia, triethanolamine, etc., may in some instances be substituted in part or all for the soda ash. That is other non-saponifying neutralizing agents may 55 be employed alone or in various admixtures as well as in -admixture with soda ash. The

amounts and concentrations of such solutions 'which give effective separation will vary with the type of oil being treated and the type of 60. neutralizing agent employed, but in general will fall within the ranges indicated for soda ash solutions. Furthermore, substantially neutral salt solutions such assolutions of sodium sulfatemay be substituted for part of the soda ash or 05 other non-saponifying neutralizing agent solu-' tions to aid in low loss centrifugal separation.

.While the processes involving continuous centrifugal separation of the soap stock from the oil result in major-savings in refining losses even 70 over prior continuous processes employing caustic alkalies, improved results over prior settling operations for separating the soap stock from the oil are accomplished in accordance with the present invention. Thus, by employing extreme- 75 ly large excesses, for example by employing from seven to twelve times the amounts of soda ash necessary to neutralize the free fatty acids andinsuring that soda ash solutions are of proper concentration during separation, for example between 12 and 20 B., an improved settling sepa- 5 ration step can be obtained such that the soap stock settles in the clearly defined layer of less volume than prior settling operations and contains less entrained oil. Also, there is no saponification of neutral oil. As in the case of the con- 10 tinuous process, other non-saponifying neutralizing agents may be substituted either in whole or in part for the soda ash or a neutral salt may be in part substituted for the neutralizing agent with somewhat less efiective results. vThus, a 15 settling operation may be employed after a continuous mixing step such as shownin Figures 1 and 2, or after a batch mixing step such as shown in Figure 3, or a part batch and 'part continuous mixing step such as shown in Figure 20 4. Also, a color reducing step may be carried out as a batch operation, although not as effectively as the continuous operations disclosed. Thus, a color-reducing agent such as a small amount of caustic soda solution may be added 26 to a batch of neutralized oil, thoroughly admixed therewith and then the color impurities allowed to settle out. Such a batch color reducing step may be employed in combination with continuous or batch neutralizing steps. Also, the water 30 washing step may be carried out as a batch operation by thoroughly admixing washing water with a body of the oil and then allowing the water and impurities contained therein to settle out of the oil. Batch vacuum drying. is also possible to be employed such that it is possible to carryout the entire process of the present invention in a single kettle arranged to be closed to the atmosphere and for having a vacuum produced therein. Also, any combination of of the invention, Even tung oil which is extremely dimcult to alkali refine because of emul- 5osion difficulties may be successfully refined by the present process employing large excesses of soda ash solutions. While the process is particularly adaptable to the refining of crude vegetable oils, so called degummed oils which have been previously treated to remove gummy materials can also be successfully refined so as to minimize refining losses. The term animal oils-is also intended to include fish oils such as sardine, menhaden, or herring oils. By the employment of the term oils or "oil in the claims I intend to embrace glyceride fats or oils, irrespective of the viscosity thereof.

This application is a continuation-in-partof my copending application, Serial No. 259,502, filed o March 3, 1939.

mixing with said 011 a non-saponifying neutralizing agent in an amount at least three timesthat necessary to neutralize said freefatty acids, and separating, bydifierence of specific gravity, the resulting soap stock from said oil while the excess of said agent is present as an aqueous solution containing a major portion of water and of proper concentration to render the soap stock easily fiowable and cause the oil to be thrown out of the soap stock;

2. The process as defined in claim 1 in which the separation-is carried out in the presence of an additional solution of a soap stock weighting material.

3. The process of refining glyceride oils and fats containing free fatty acids, which comprises, mixing with said oil a non-saponifying neutralizing agent in an amount at least three times that necessary to neutralize said free fatty acids, the

neutralizing agent being added as an aqueous solution containing a major portion of water and of proper concentration ,to render the soap stockeasily fiowable and minimize entrainment of oil in the soap stock when said soap stock is separated from said oil, and separating said soap stock from said oil, by difference in specific gravity. I

4. The process as defined in claim 3 in which an additional solution of soap stock weighting material is added to the mixture of oil and soap stock prior .to separation thereof.

5. The process of refining glyceride oils and fats containing free fatty acids, which comprises, mixing soda ash with said oil in an amount at least three times that necessary to neutralize said free fatty acids, and centrifugally separating the resulting soap stock from said oil by difference in specific gravity while the excess of said soda ash is present as an aqueous solution of proper concentration to render the soap stock centrifugally separable whereby to minimize entrainment of the oil in the soap stock.

6. The process of refining glyceride oils and fats containing free fatty acids, which comprises, mixing soda ash with said oii in an amount at least threetimes that necessary to neutralize said free fatty acids, and continuously centrifugally separating the resulting soap stock from said oil while the excess of said soda ash is present as anaqueous solution of proper concentration to render said soap stock centrifugally separable.

'I. The process of refining glyceride oils-and fats containing free fatty acids, which comprises, mixing sufficient soda ash with said oil to provide an amount between five and twelve times that necessary to neutralize said free fatty acids, neutralizing the said free fatty acids by the soda ash in the presence of water, continuously centrifugally separating the resulting soap stock from said oil at a temperature between 160 and 210 F. while the excess of said soda ash is present as an aqueous solution of a concentration be-, tween approximately 3 and B.

8. The process of refining glyceride oils and fats containing free fatty acids, which comprises,

mixing with said oil soda ash solution in an amount not less than three times that theoretically required for neutralizing free fatty acids 'and in sufficient amount and of proper concen tration to neutralize said free fatty acids and to sufliciently weight the resultant soap stock for continuous centrifugal separation from said oil,

' thereafter delivering said mixture to a continuous centrifugal-separator and therein separating said soap stock from said oil.

9. The process of refining glyceride oils and L foots' from the oil.

s 7 fats containing free fatty acids, which comprises, mixing sufiicient soda ash with said oil to neutralize said free fatty acids and to substantially prevent formation of carbon dioxide, thereafter adding suflicient soda ash solution of proper con centration to the resulting mixture of oil and soap stock to bring the concentration of excess soda ash solution in said mixture to condition the soap stock for continuous centrifugal separation of said soap stock from said oil with minimum entrainment of neutral oil, and thereafter continuously centrifugally separating said soap added during said process being not less than three times the amount theoretically necessary to neutralize the free fatty acids.

10. The process of refining glyceride oils and fats containing free fatty acids, which comprises, adding to a body of said oil soda ash solution in s an amount at least three times that necessary to theoretically neutralize the free fatty acids and of proper concentration to neutralize said free fatty acids and condition the mixture for continuous centrifugal separation of the resulting soap stock from said 011, agitating said oil and solution to obtain a thorough admixture and cause said soda ash to neutralize said free fatty acids, continuing the agitation of said mixture and withdrawing a stream thereof during said 11. A continuous process of refining glycerideoils and fats which comprises the steps of: pumpstock from said oil, the total amount of soda ash ing a metered stream of oil into contact with a metered stream of soda ash solution with the soda ash present in said solution being more than several times that required to theoretically neutralize the free fatty acids contained in said oil, 7

pumping the resultant mixture through a heating zone while excluding" air, elevating the ternperature of the mixture as it passes through said zone to at least 160 F., conditioning the resultant mixture of soap stock and refined oil for the act of centrifugalseparation by introducing to the advancing stream thereof an aqueous solution of additional soda ash in an amount and concentration-sufiicient to weight the soap stock and thereby improve itsv centrifugal separability and continuously centrifugally separating the thus conditioned soap stock from the refined oil.

12. The process as defined in claim 11 wherein color is removed from the refined oil by introducing a dilute solution of caustic alkali into a stream of oil continuously removed from the centrifugal in an amount insufiicient to effect substantial saponification of the neutral oil and promptly centrifugally separatingthe resultant 13. A continuous process for the refining of glyceride oils and fats containing free fattyacids and color impurities which comprises the steps of: effecting substantial neutralization of the free fatty acids and a substantial removal of the color impurities by an aqueous solution of a non-saponifying reagent containing a major portion of water and in an amount at least several times that theoretically required to neutralize said free fatty acids, conditioning the mixture of foots and oil forthe act of centrifugal separation and centrifugally separating the foots said separation.

14. The process as defined in claim 13 in which said conditioning of the facts is facilitated by the employment of a sufficient excess of .non-saponifying reagent to weight the foots and improve their separability.

15. The process as defined in claim 13 in which the conditioning is aided by the introduction of a hydrating and weighting medium at a time subsequent to the neutralization and prior to separation.

16. The process as defined in claim 13 in which an aqueous solution of soda ash is introduced after mixing and prior tocentrifugal separation in an amount suificient to improve the separae bility of the foots by centrifugal separation- 17. The process as defined in claim 13 in which the non-saponifying reagent comprises soda ash and is mixed with the oil under pressure and out of contact with the atmosphere, thus g an elevation in temperature substantially above 19. The process as defined in claim 13 in which the conditioning includes the step of subjecting the mixture of oil and soap stock, during continuous fiow and out of contact with the air, to

an elevation in temperature to not less than 20 The rocess as defined in claim 13 in which "cient to partially remove said free fatty acids 7 the thus refined 011 while said soda. ash solution and color impurities, thereafter adding to the mixture an additional quantity of soda ash in aqueous solution sufiicient to complete the neutralization of the remaining free fatty acids and to effect further reduction of the color impurities, the total amount of soda ash added in the process being not less than three times that theoretically required for neutralizing said free fatty acids, centrifugally separating the resultant foots from is present in a quantity suficient to render the soap stock centrifugally separable.

23. A process for the refining of glyceride oils and fats which comprises the steps of admixing with the oil anon-saponifying reagent in an.

amount largely in excess of that theoretically required to neutralize the free fatty acidspresent in said 011 and not less than 5 times that required for such neutralization whereby to render the resultant soap stock capable of centrifugal separation without entrainment losses, effecting such neutralization and thereduction of color while said reagent is present in the form of an aqueous solution containing a major portion of water and thereafter continuously centrifugally separating the thus modified and weighted soap stock from the refined oil.

as. A continuous process for the refining of glyceride oils and fats which comprises the steps of: mixing soda ash with said glyceride, neutral izing the free fatty acids contained in said glyceride in the presence of moisture, continuously converting the resulting foots from a centrifugally inseparable to a centrifugally separable form by continuously incorporating therewith an aqueous medium and thereafter continuously centrifugally separating "the thus conditioned fonts from the refined oil in the presence of suflicient alkali to prevent gas from interfering with said centrifugal separation.

25. The process as defined .in claim 24 in which the mixture of soda ash and glyceride is subjected to heat and pressure during stream flow thereof and while closed from the atmosphere.

26. The process as defined in claim 24 in which a stream of an aqueous solution ofsoda ash and a stream of the glyceride are continuously mixed and advanced under pressure through a heating zone.

2?. The process as defined in claim 24 in which the added aqueous medium comprises a salt constituting a weighting agent.

2s. The process as defined in claim 24 in which the amount of soda ash added during said process is notless than three times that theoretically re quired to neutralize the said free fatty acids in the glyceride.

29. The process as defined in claim 24 in which the temperature of the refined 011 following centrifugationis reduced and wherein the last traces of color are removed therefrom by introducing a dilute solution of caustic alkali to a stream of oil continuously removed from the centrifugal in an amount insufiicient to eflect substantial saponification of, the neutral oil and promptly centrifugally Separating the resultant foots from the oil.

30. Theprocess as defined in claim 24 in which the temperature of the refined oil following cantrifugation is reduced and wherein the last traces of color are removed therefrom by introducing a dilute solution of caustic alkali to a streamof oil continuously removed from the centrifugal in an amount insufilcient to efifect substantial saponification of the neutral oil and in which the stream of oil is continuously reheated and subjected to prompt centrifugal separation for the 3mm CLAYTON.

' CERTIFICATE OF CO ERECTION.

Patent No. 2, 190,59LL. February I} 19b0, V

BENJAMIN CLAYTON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, sec ond column, line 9, for the word "stocks" read stock; line 58, for "axchange" read exchange; page 5, first column, line 71 after "mixing" insert device; page LL, second column, line 61, for "by" read but; and that the said Let ters Patent should be read with this correction therein that the same may conform tothe record of the case in the Patent Office.

Signed and sealed this 9th day of April, A. D. 1921.0,

Henry Van Arsdale, (Seal) Acting Commissioner of Patent s. 

